


Only You Contain the Key to My Heart

by kitkatwrites



Category: Chain of Gold - Cassandra Clare, The Last Hours Series - Cassandra Clare
Genre: Angst, Cordelia Carstairs is a good sister, I started this book hating Alastair and I finished it wiling to die for him, M/M, Making Out, Making Up, Thomas loves Alastair’s natural hair, Thomastair, can you tell I tried and failed at writing in a 1900’s style, oneshot I guess, unless??
Language: English
Status: Completed
Published: 2020-03-07
Updated: 2020-03-07
Packaged: 2021-02-28 22:48:37
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,445
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23045047
Author URL: https://archiveofourown.org/users/kitkatwrites/pseuds/kitkatwrites
Summary: Alastair laid on his back, twirling a blade between his fingers. For the past couple of weeks, he had found himself in this same sorry state: completely numb to the world around him, or as Cordelia had diagnosed him, heartbroken. Alastair considered her diagnosis incredibly untrue and stupid. He was strong, and powerful, and who was he kidding he was completely heartbroken. Which, he considered, completely unfair and unjust.
Relationships: Alastair Carstairs & Thomas Lightwood, Alastair Carstairs/Thomas Lightwood
Comments: 5
Kudos: 182





	Only You Contain the Key to My Heart

**Author's Note:**

> I started this less than an hour after I finished the book so here’s what I’m hoping will happen in Chain of Iron. If nothing similar to this happens I will cry.

Alastair laid on his back, twirling a blade between his fingers. For the past couple of weeks, he had found himself in this same sorry state: completely numb to the world around him, or as Cordelia had diagnosed him, heartbroken. Alastair considered her diagnosis incredibly untrue and stupid. He was strong, and powerful, and who was he kidding he was completely heartbroken. Which, he considered, completely unfair and unjust.

Alastair had managed to break free from his relationship with Charles, which never really felt like a real relationship due to the fact that he was forced to secrecy and Charles was willingly engaged to a woman. But it didn’t matter in the end, because Alastair had ridded himself of Charles and was ready to pursue a certain brown-haired giant when his chances got completely ruined by one Matthew Fairchild. Funny, how the Fairchilds always seemed to ruin his romantic pursuits. But alas, it couldn't be helped. Alastair had said every single word that came out of Matthew’s mouth, much to his dismay and regret. If only they had known that life at The Academy was kill or be killed, and Alastair enjoyed the land of the living. Well, they must have known that, on account of the fact that all of them had attended The Academy together. Alastair assumed they just didn’t enjoy living as much as he did. But it didn’t matter in the end, because Alastair had royally screwed up his chances with Thomas Lightwood.

So there he was, his back on his bedsheets as he stared at the dagger he twirled expertly between his fingers. A sudden thought to plunge the dagger between his ribs flashed across his mind, and he went into such a state of shock that he almost dropped the blade onto his chest. He guessed he didn’t completely enjoy the land of the living as much as he had originally thought.

“Alastair,” Cordelia called from the doorway, “I’m going to train at the Institute with Lucie. I would forever be in your debt if you joined me, you know how bad my feet placements can be.” She was buttering him up, that much was clear. Cordelia was probably concerned for him; Alastair was never this sullen and depressed. He sighed, sitting up to face his sister.

“Fine, but if any of those ‘Merry Men’ show up I will have to take my leave before they send a dagger my way.”

“Alright, but hurry up before I leave without you,” Cordelia teased.

Alastair swung his feet off his bed with a grunt and began lacing up his boots before tucking the dagger into his belt. One could never be too careful.

~~~

Stepping into the London Institute training room, Alastair was grateful to find the room devoid of any of his sister’s male companions. Lucie stood at one end, expertly throwing axes at a target. Cordelia clapped in support and her future  _ parabatai _ turned towards her with a smile.

“Daisy! I’m so glad you could make it, you know how lonesome it can get without a sparring partner.” Cordelia hummed in understanding as she wrapped her arms around Lucie in a warm embrace.

“Would you mind if we threw knives for a bit?” Cordelia asked, drawing a dagger from her belt, “My form is absolutely dreadful, which is why I brought Alastair along.” He gave Lucie a tiny nod as she regarded him with a cool gaze. Great. Yet another person despised him.

If Cordelia noticed her friend’s indifference to her brother, she didn’t say anything. The two girls lined up and began throwing, their knives cutting expertly through the air. Cordelia sent a knife spiraling through the air, hitting one of the outer rings.

“Oh drat,” she swore. Alastair walked up behind his sister and grabbed her shoulders before kicking her foot out.

“You need to turn your foot out Layla, if you want to be more accurate. Now, again.” Alastair backed up, watching her feet carefully. Cordelia lined up her dagger before letting it fly, straight into the bullseye.

She squealed and clapped her hands together before turning to Alastair. “Thank you, without your guidance I would have died long ago in battle.” Alastair smiled at his sister’s comment.

“Don’t sell me too high now, what if you  _ do _ end up dying? Then I must be to blame for not instructing you correctly.” Cordelia gasped.

“Then I will have to put it in my will. ‘If I am killed by demons, it is not Alastair’s fault. He was not there to remind me to turn my foot out.’” The two siblings grinned at each other with a newfound fondness before the doors burst open.

The room was filled with chattering boys before they stopped abruptly, staring at the three Shadowhunters already practicing. Alastair felt his heart sink as he stared at the Merry Thieves. Of course  _ they _ would be there; the training room was open to all, after all. But why did  _ he  _ have to be there too?

Thomas took one look at Alastair before turning on his heels and walking right out of the room, much to Alastair’s dismay. He heard Cordelia suck in her breath behind him, her sorrow for her brother almost palpable. Alastair paid her no mind and began to walk after Thomas.

On his way out the door, Matthew reached out and grabbed the taller boy above his elbow. “Don’t you dare hurt a hair on his head or I will take great pleasure in ripping you limb from limb as you beg for mercy, do you understand me?” Matthew’s dark green eyes seemed to bore holes into Alastair’s heart as he spit at the boy.

Alastair scoffed as he tore his arm out of Matthew’s grip. “Take care of yourself before you throw yourself blindly in front of others, I know a drunkard when I see him.” Matthew blanched as Alastair stormed off, fuming. He tried to keep a clear head as he searched for Thomas, but his search ended prematurely when the boy appeared in front of his path. Alastair stared wide-eyed at the taller boy, confused.

“Thomas, wha-”

“What do you  _ want _ with me,” Thomas asked angrily, “I mean, you spread awful rumors about me at school and now you act as if you desire to be friends, but friends would never say something so cruel and hurtful. You are a mystery I don’t wish to solve, Alastair Carstiars, now leave me be before my actions towards you turn violent.”

“Thomas please, just give me a chance to explain,” he begged, “Words can’t express how sorry I am and how much pain I have felt over causing you pain. At school, I was scared. I needed to be seen as someone important, someone not to be messed with. That is why I acted the way I did. I’m not excusing my actions and I don’t expect you to forgive me, I know I was acting terribly and you deserve to feel any level of anger towards me. But know this: I love you more than you could ever imagine and I will never stop loving you, even if you never feel the same.” With a gasp, Alastair’s mouth snapped shut. He felt as if the words had been forced out of his mouth and now that he was done, he no longer had a use for talking.

Warm, hazel eyes stared back at his own black ones, searching for something in his face. Instantly, Thomas surged forward to press his lips against the shorter boy. Alastair gasped into the kiss, tilting his head up to better meet Thomas’ lips. Pushing Thomas backwards, Alastair forced the boy up against the wall as he continued to mouth at his lips, desperate for more. Thomas groaned against his lips as Alastair moved his mouth down to press kisses to his jawline and neck.

“Alastair, my beautiful boy,” Thomas whispered, “I have been in love with you since Paris, I,” he ceased talking as Alastair pressed his lips back to Thomas’, effectively silencing the boy. Alastair ground up onto Thomas and the taller boy moaned, grabbing onto the other boy’s hair.

“I never got to tell you,” Thomas pulled away and stared into Alastair’s lust-filled eyes, “I’ve always liked your dark hair better. It matches your complexion beautifully.” He ran his fingers gently along Alastair’s cheek, thumbing his bottom lip.

“Well then,” Alastair said with a smile, “It’s a good thing I’ve dyed it back.” Thomas hummed.

“Yes, a  _ very _ good thing.”

They shared sloppy grins before their lips pressed together once more; both boys secretly hoped they would never have to let go.

**Author's Note:**

> Eyy thanks for checking this out, thomastair has stolen my heart and ran away with it and the only way I can win it back is by writing self-indulgent fics where they can be happy together. Consider checking me out on tumblr? @hornyforsharks


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